The present disclosure relates to sheet feed devices, image forming apparatuses including the sheet feed devices, and a method for controlling the sheet feed devices.
In general, an image forming apparatus includes a sheet feed device that has: a sheet delivery portion that feeds recording sheets to a conveying path from a sheet receiver such as a sheet cassette (sheet feed cassette) or a manual sheet feed tray; and a control portion that controls the sheet delivery portion. The sheet delivery portion includes a pickup roller that rotates in contact with the recording sheets to feed the recording sheets from the sheet receiver. The sheet cassette is mounted so as to be drawable from a housing. The pickup roller is an example of a sheet feed roller.
Further, a sheet detection sensor that detects the recording sheets is provided in the conveying path in many cases. A timing at which the recording sheet is to be fed to an image forming portion is controlled according to a timing at which the sheet detection sensor performs detection.
Further, it is known that, in a case where the image forming apparatus includes a plurality of the sheet delivery portions, automatic change control is performed. The automatic change control is a control for sequentially feeding a plurality of the recording sheets while automatically selecting, according to a predetermined selection rule, the sheet delivery portion for which a sheet feeding operation is to be performed.
Further, it is known that intervals at which the recording sheets are fed are adjusted according to an actual value of a time in which the recording sheet is conveyed.